The monolithic integration of lenses with photoelectric elements is desirable for redirecting light rays within the elements to concentrate light therein or to provide more efficient light coupling therefore. Integrated lenses may also be useful for improving the coupling of light from photoelectric elements to optical fibers.
U.S. Pat. No. 3,763,372 to Fedotowsky et al discloses a device having zone plate optics monolithically integrated with a phase filter and a photoelectric element to provide an image conforming to the shape of the photoelectric element after multiple reflections of a light beam within the device.
U.S. Pat. No. 3,981,023 to King et al discloses a light emitting diode structure formed on a substrate and having one or more convex lenses extending into an aperture through the substrate.
U.S. Pat. No. 4,339,689 to Yamanaka et al discloses a light emitting diode having a protrusion formed unitarily on a surface of a semiconductor clad layer for facing an input end of a light guide to effect light coupling therewith. The method for forming the light emitting diode includes the step of selectively etching the substrate to form a through-hole to expose at least the protrusion of the clad layer.
U.S. Pat. Nos. 5,038,354 and 5,181,220 to Yagi disclose a semiconductor light emitting and light concentrating device having a multiple diffraction ring system for collecting and focusing the light emitted from a semiconductor light emitting element of the device.
U.S. Pat. Nos. 4,025,157 and 4,108,622 to Martin disclose a miniature optical lens that is a composite material shaped in a configuration of pairs of parallel rectangular side surfaces, each such pair of surfaces being disposed orthogonally relative to each other pair. The composition of the semiconductor material of the miniature optical lens varies between at least one pair of the parallel rectangular flat surfaces for causing a predetermined gradient of refraction of the order of approximately one percent between the surfaces, thereby producing a desired focal length for wavelengths of light energy transmitted orthogonal to the gradient index of refraction (i.e. parallel to the surfaces).
U.S. Pat. No. 4,956,000 to Reeber discloses a method for fabricating a gradient lens by a spatially non-uniform deposition process, with the lens material being directed through an orifice of a rotating lens-shaping element, and the lens size and shape determined by the selective direction and condensation of vaporized lens material onto a substrate.
The unitary lens semiconductor device of the present invention represents an improvement over prior art devices, and has an advantage that one or more unitary lenses may be formed adjacent to and self-aligned with a light-active region for the generation or detection of light, while providing in some embodiments a planar outer surface for the device.
Another advantage of the unitary lens semiconductor device according to the present invention is that the vertical placement of one or more unitary lenses may be determined relative to a substrate, light-active region, or other optical or electronic element during growth of epitaxial layers upon a semiconductor substrate, with the unitary lenses later formed either adjacent to an outer surface of the device, or buried more deeply within the device (as, for example, below a stack mirror, or adjacent to a light-active region).
A further advantage of the present invention is that the position and shape of the unitary lens may be defined in part by a composition of one or more semiconductor layers during growth of the layers.
Another advantage of the present invention is that the unitary lens may be located within a resonant cavity formed by a pair of stack mirrors to provide means for defining a lateral mode for the light generated within the device.
Yet another advantage of the present invention is that the unitary lens may define a light-active area of a light-active region in a unitary lens semiconductor device, thereby providing for an accurate self-alignment of the lens and light-active area with a common optical axis.
Still another advantage of the present invention is that the unitary lens may be electrically conducting and provide a current channel for the flow of an electrical current into or out from a light-active region of the device.
Another advantage of the unitary lens semiconductor device according to the present invention is that an efficiency for coupling light rays into or out from the device may be improved by the unitary lens formed adjacent to a light-active region in the device.
These and other advantages of the unitary lens semiconductor devices and method of the present invention will become evident to those skilled in the art.